Refrigeration



A ril 22, 1941. c. c. COONS ETAL REFRIGERATION Filed on 51, 1940 s R g m mm 8 E F f m d. N 74 E N R V 0 s w wfi A a l P W y h 6 u llllllllllllllIllllllllllllllllllll I Patented Apr. 22, 1941 REFRIGERATION Curtis C. Coons, North Canton, Ohio, and Rudolph S. Nelson, Larchmont, N. Y., assignors to The Hoover Company, North Canton, Ohio, a. corporation of Ohio Application October 31, 1940, Serial No. 363,768 .21 Claims. (01. 62-1195) The present invention relates to the art of refrigeration and more particularly to a novel refrigerating system of the type utilizing a power driven circulating element to circulate an inert pressure equalizing medium .through certain portions of the system.

Previous three-fluid absorption refrigerating systems of the type utilizing a power drivenpressure equalizing medium circulator possessed certain disadvantages due to the fact that the high fan pressure impressed upon the evaporator was carried back through various portions of the system including the condenser and rectifier to the analyzer, thereby depressing the liquid level in the boiler-analyzer system. In order to utilize a system of this type, the entire boiler analyzer structure is lowered to an extent which prohibitively increases the height of the system which is sharply limited by the space limitations imposed by domestic refrigerating cabinets. Furthermore, such constructions introduce pressure fluctuations in the solution circuit which are carried through the weak solution line to the pump, thereby causing the pump to operate erratically or not at all. Additionally, the pressure produced by the pump is used up in overcoming the resistance of various parts of the pressure equalizing medium circuit, and improper proportioning of the resistance of the various parts of the system frequently reflects in the solution vcircuit to an extent suflicient to prevent solution circulation and/or to cause the solution to block the absorber conduit.

In a three-fluid system utilizing a gas circulator to circulate the inert gas through an inert gas circuit having a high resistance, as where the gas must be passed through or introduced into liquid present in the system, an appreciable pressure differential is produced across the circulator. This pressure differential is dissipated by varying amounts in different parts of the inert gas circult as the gas flows therethrough. Consequently appreciable pressure differences occur between different parts of the gas circuit which tend to displace liquid levels in the system and to create compensating pressure balancing liquid columns. Displacement of liquid levels is undesirable in certain parts of the system as it requires displacement of various vessels and renders purging of the consenser difiicult.

As a result of these various limitations upon previous systems, they are unable to utilize the highly eflicient .and desirable non-submerged plate-type analyzer without greatly lowering the level of the boiler-analyzer and providing a. pressure balancing liquid column in the strong solution circuit between the absorber and the analyzer. Previous systems are provided with a solution reservoir, but common practice has been .to place the reservoir in such position that it substantially constant and in which relatively.

large pressure differentials are permitted to exist between various parts of the solution circuit. The solution circuit is so connected into the other. parts of the apparatus that it is not aifected by transient conditions produced within various parts of the refrigerating system, and the strong solution return conduit is subjected substantially to the same pressure at each end thereof whereby it is not affected by the discharge pressure of the circulating fan.

It is a further object of, this invention to provide an absorption refrigerating system of the type above described in which the generator or boiler-analyzer assembly and the strong solution conduit are effectively shielded from the high pressure prevailing in the evaporator and from the discharge pressure of the circulating fan, thereby permitting the relative positions ofthe generator and absorber to be determined independently of the pressures developed by the fan.

It is a further object of the invention to provide a solution circuit in an absorption refrigerating system of th type above described in which the solution reservoir is placed in the weak solution circuit in such fashion that it effectively stabilizes the solution levels in the. circuit and particularly on the circulating gas lift pump to provide for steady, uniform and eflicient operating conditions- It is a further object of the invention to pro vide a refrigerating system of the type above line from the absorber, thereby assuring that the same pressure shall exist throughout the strong solution and vapor circuits.

It is a further object of the invention to provide an absorption refrigerating system in which the generator or boiler-analyzer.assembly may extend substantially to the level of the absorber.

It is a further object of the invention to provide a refrigerating system of the above described character in which the strong solution line is positioned to absorb waste heat from the system, thereby to increase the eificiency thereof and to utilize the thermosyphonic action of the waste heat to aid the solution fiow.

It is a further object of one form of the invention to render the operation of the solution circuit entirely independent of the relative distribution of the resistance in the gas circuit between the evaporator and the gas heat exchanger.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawing, in which:

Figure 1 is a diagrammatic representation of a refrigerating system embodying the present invention with certain portions thereof drawn isometrically and on an enlarged scale.

Figure 2 is an enlarged scale isometric view of a modified form of the invention.

Referring now to the drawing in detail, and first to Figure 1 thereof, there is disclosed a three-fluid absorption refrigerating system comprising a generator including a boiler B and an analyzer D, an air-cooled rectifier R, a tubular air-cooled condenser C, an evaporator E, a gas heat exchanger H, a tubular air-cooled absorber A, a solution reservoir S, a liquid heat exchanger L, and a circulating fan F which is driven by an electrical motor M. The above described elements are interconnected by various conduits to form a plurality of gas and liquid circuits constituting a complete refrigerating system to which reference will be made in more detail hereinafter.

The refrigerating system will be charged with a suitable refrigerant, such as ammonia, a suitable absorbent, such as water, and a suitable inert pressure equalizing medium, such as nitrogen.

The generator may be heated in any suitable manner as by an electrical cartridge heater or by a gas burner as may be desired. The circulating motor M and the heater for the generator may be controlled in any suitable or desired manner.- A preferred control mechanism is disclosed in the co-pending application of Curtis C. Coons, Serial No. 148,424, filed June 16, 1937.

The application of heat to the boiler B liberates refrigerant vapor from the strong solution therein contained. The vapor so liberated passes upwardly through the analyzer D-passlng backwardly and forwardly across the staggered baflle .plates l2 in counterfiow relationship to strong solution flowing downwardly through the analyzer. Further refrigerant vapor is generated in the analyzer by the heat of condensation of absorption solution vapor generated in boiler B.

The refrigerant vapor is conducted from the mg vertically for purposes of convenience.

upper portion of the analyzer D to the upper portion of the condenser C through a conduit l3 which includes the air-cooled rectifier R wherein any vapor of absorption solution passing through the analyzer is condensed and is returned to the analyzer through the conduit I3. The refrigerant vapor is liquefied in the condenser by heat exchange relation with atmospheric air and is discharged from the bottom portion thereof through a conduit l5 into a downwardly extending conduit IS. The bottom portion of the conduit I'6 connects to the bottom portion of an upwardly extending conduit l'l through a U-bend 18. The conduit I6 is appreciably longer than the conduit I! for a purpose to be described hereinafter. The conduit ll opens at its upper end into a conduit 20 which discharges into the evaporator in a manner to be described more fully hereinafter.

The weak solution formed in the generator by the generation of refrigerant vapor therefrom is conveyed from the boiler through a conduit 22, the inner path of the liquid heat exchanger L, and a conduit 23 into the solution reservoir S. The weak solution is conveyed from the solution reservoir S through a U-shaped conduit 24 which opens into the bight portion of a U-shaped twin gas lift pump 25 which discharges into an extension conduit 26 on the upper portion of the absorber A. It is apparent that the conduit 26 is materially above the solution level normally prevailing in the boiler-analyzer reservoir system wherefore some means must be provided to elevate the absorption solution into the conduit 26. For this purpose a small bleed conduit 21 is connected to the discharge conduit 28 of the circulating fan F and branches into a pair of conduits 29 and 30 each of which opens into one of the legs of the twin gas lift pump 25 below the solution level normally prevailing in the reservoir whereby the weak solution is elevated into the absorber by gas lift action.

The absorber A has been illustrated as extend- The absorber may be in any plane from the vertical to a plane slightly inclined to the horizontal which is the preferred arrangement because of the small vertical space occupied by an absorber in this position.

In the absorber the weak solution flows downwardly by gravity in counterfiow to the rich pressure equalizing medium refrigerant vapor mixture flowing upwardly therethrough in a manner to be described more fully hereinafter. The refrigerant vapor content of the mixture is absorbed in the absorption solution and the heat of absorption is rejected to the surrounding air by the aircooling fins which are mounted on the exterior walls of the absorber vessel. The strong solution formed in the absorber collects in the bottom portion thereof and discharges into a conduit 32 which opens into the outer path of the liquid heat exchanger L. From the outer path of the liquid heat exchanger L the strong solution is conveyed to the upper portion of the analyzer D by a strong solution return conduit 33 which is in heat exchange relationship with the top portion of the boiler B and with the side wall of the vertically extending analyzer D for a purpose to be defined more fully hereinafter.

The lean pressure equalizing medium refrigerant vapor mixture formed in the absorber A is taken from the upper portion thereof through the conduit 35 into the suction side of the cir-.

sure and discharged through the conduit 28 into the outer path of the gas heat exchanger H. The pressure equalizing medium under pressure is conveyed from the outer path of the gas heat exchanger H through a downwardly extending conduit .36 into the bottom portion of the evaporator E.

The evaporator vE illustrated herein is that form of evaporator illustrated and described in detail in the co-pending application of Curtis C. Coons and William H. Kitto, Serial No. 220,189, filed July th, 1938. This specific evaporator construction forms no part of my invention. Accordingly, the evaporator shown may be considered representative of any suitable evaporator so far as respects the present invention. Briefly, the evaporator herein disclosed comprises three horizontally extending coil .sections 31, 38 and 39 and an upper enlarged finned box-cooling evaporator section 40. The conduit 3G opens into the coil section 31. The coil sections 31 and 38 are connected by a riser conduit 4|. The coil sections 38 and 39 are connected by a riser conduit 42, and the coil sections 39 of the box-cooling conduit 40 are connected by a riser conduit 43. The evaporator is constructed and arranged so that it is adapted to be enclosed in a suitable housing including shelves resting on the various coil sections upon which ice freezing trays may conveniently be mounted. Other forms and arrangements of evaporators may, however, be used'without departing from the spirit or the scope of the present invention. I

The conduit 20 opens into the bottom portion of the conduit 36 whereby the liquid refrigerant supplied to the evaporator enters the same simultaneously with the pressure equalizing medium which is placed under pressure by the circulating fan F. The diameter of the conduits forming the evaporator are relatively small wherefore the pressure equalizing medium flows through such evaporator conduits with a higher velocity than has been the previous practice in this art. The rapidly flowing pressure equalizing medium sweeps or drags the liquid refrigerant with it through the evaporator into the box-cooling conduit 40 as the refrigerant is evaporating to produce refrigeration. In the conduit 40 the velocity of the inert gas stream is relatively slower by reason of the large diameter of that conduit and the liquid refrigerant flows therethrough simply by gravity.

The rich pressure equalizing medium refrigerant vapor mixture formed in the evaporator is conducted therefrom into the inner path of the gas heat exchanger H through a conduit 45. The opposite end of the gas heat exchanger I-I communicates with the bottom portion of the absorber A through a conduit 46. In the absorber A the rich pressure equalizing medium and refrigerant vapor mixture flows upwardly in counterfl-ow to absorption solution to absorb the refrigerant vapor content of the mixture in the manner heretofore described.

The bottom coil 31 of the evaporator is pro The solution reservoir S is vented through a conduit 50 into the suction conduit 35 of the circulating fan.

The operation and advantages of this form of the invention will now be described: The circulating fan F places the pressure equalizing medium discharged therefrom under a small pressure, for example, a pressure of approximately 4 of water, Though this pressure differential is small, it can cause serious diiilculties in various parts of the system because it may'necessitate the rearrangement of the levels of various 'vessels in the solution and other circuits in order to provide proper flow of fluids through the system. With the arrangement herein defined, the generator is shielded from the effects of this fan pressure in the following manner: The liquid refrigerant flowing through the conduits IS, IS

and I1 is flowing into an area of relatively high pressure, namely, the high pressure discharge conduirt. 36 which connects directly to the discharge conduit of the fan F through the gas heat exchanger H.

In order to prevent the relatively high pressure prevailing in the conduit 36 from being carried back through the condenser discharge conduit, the condenser, and conduit l3 or to the generator, the conduit l6 has been made appreciably longer than the conduit II wherefore a pressure balancing column ofliquid is formed in the conduit l6 which extends abo e the point of connection between the conduits l1 and 20 a distance suflicient to balance the increased pressure in conduit 36 produced by the circulating fan F. As a result of this construction, the pressure prevailing in the system comprising the generator, the conduit l3 and condenser C is lower than that prevailing in the conduit 36. The analyzer is also connected through the conduit 33, liquid heat exchanger L, and conduit 32 to the absorber, but it will be noted that its point of connection with the absorber is such that the pressure prevailing in the absorber at that point is approximately equal to the suction pressure of the gas circulating fan. Also the vent conduit 49 from the condenser system opens into the absorber A at the same point at which the conduit 32 opens thereint-o whereby substantially the same pressure prevails throughout the system including the condenser, generator, and strong solution return conduit.

The solution reservoir S is vented directly into. the suction inlet of the circulating fan F by the conduit 50, wherefore the weak solution circuit as well as the generator is subjected to the suction pressure of the circulating fan. This possesses the additional advantage that the gas lift pump is enabled to operate with the maximum possible pressure differential present in the system, thereby improving the efliciency of that pump and increasing its possible pumping range to the maximum value.

The entire solution circuit, the condenser, the absorber, and the boiler-analyzer are subjected to substantially the suction pressure of the fan by the arrangement of the vents 49 and 50 and the reservoir. Accordingly, the generator and absorber may be arranged very compactly vertically because the present invention provides means preventing the pressure differential created by the gas circul-ator from aifecting the liquid levels in the absorber and generator. The circulating fan operates at a constant speed and is not material 1y affected by changes in pressure conditions which sometimes occur in the evaporator-gas heat exchanger circuits; therefore, these pressure fluctuations are not reflected in the absorption solution circuit and do not produce transient and undesirable conditions therein. Moreover, by placing the solution reservoir in the. weak solution circuit the large area. of solution therein contained prevents the effective liquid level on the gas lift pump from fluctuating due to transient conditions sometimes occurring in the generator.

It will be apparent that vent 49 also serves to purge the condenser-boiler assembly of inert gas which may escape thereinto from the inert gas circuit. Some inert gas is sought to be carried into the boiler along with the rich absorption solution and passes from there into the condenser. If means is not provided for conveying this inert gas back into the inert gas circuit, suflicient thereof will collect in the condenser to interfere with the condensation of refrigerant vapor, and finally the partial pressure of the inert gas in the condenser will become so high that substantially no refrigerant vapor can be condensed. When this condition prevails, it is of course impossible to produce refrigeration. However, the present construction entirely avoids the possibility of such a condition ever existing because vent 49 will conduct the inert gas back to its proper habitat in the system. But it is to be noted that by the novel construction and arrangement of this vent with respect to the high and-low pressure sides of the gas circulating means and with respect to the pres-sure balancing device, the purging function is" accomplished without adversely affecting the pressure balancing device or the other liquid levels in the system.

One ofthe most important advantages of the above described construction and arrangement is the fact that the entire generator, solution circuit and'condenser system is not affected by the pressure prevailing in the conduit 36; therefore, it is not necessary to lower the analyzer inlet to a. level below the strong solution outlet of the absorber to provide for a liquid column in the conduit 32 above the level of the junction of the analyzer D and the conduit 33 of sufiicient'height to balance the pressure difference existing between the bottom portion of the absorber A and the evaporator inlet conduit 36. This permits the boiler-analyzer system to be raised several inches in height which is of extreme importance due to the rigid space limitations imposed upon domestic refrigerating systems by the cabinets into whichthey must be placed, and it also permits the use of the efficient non-submerged bafi'ie type analyzer illustrated, with resulting improvement in the efii ciency of the system as a whole.

Referring now to Figure 2, there is disclosed a modified form of the invention. This form of the invention is designed and intended to be utilized with the system disclosed in Figure 1 and is identical therewith in every respect except in a few particulars to be noted hereinafter. Those portions of the construction of Figure 2 which are identical with the construction of Figure l are given the same reference characters primed.

In this form of the invention the rich mixture discharge conduit 45' of the evaporator and the lean mixture inlet conduit of the evapo- The condenser discharge conduit l5 now opens into the U-shaped conduit 60 at a. level above the level of the intersection of the conduits 36 and 60. By reason of this construction the pressure prevailing in the conduit I5 is .that prevailing in the discharge conduit of the evaporator. The pressure difference between the conduits 36' and 45', which in this construction is substantially the major portion of the discharge pressure of the circulating fan F, is balanced by a liquid column in the leg of the conduit opening into the conduit 45' which extends above the level of the junction of the conduits E0 and 36'. This construction replaces the conduit construction l6, l1 and vent 49 disclosed in Figure 1.

In this form of the invention the pressure prevailing in the condenser, conduit I3 and the refrigerant generator will be greater than that prevailing in the conduit 32 by an amount equal to the pressure drop through the gas heat exchanger H. However, with some preferred constructions of gas" heat exchanger the resistance to gas flow therethrough is very small, wherefore the con-. struction in Figure 2 may be utilized without adversely affecting the solution circuit. The construction of Figure 2 is preferred where it is possible to use'the same because it is simpler and cheaper to manufacture than the construction illustrated in Figure 1.

,A illustrated in Figure 2, the condenser could only extend to a level slightly. above the level of the middle coil section 38', but this has been done merely for the convenience of illustration, as the point of connection between the conduits 3t and Gil could be lowered to the level of the coil section 3i without interfering in any manner with the operation of the system. In this event the condenser should extend to a level only a few inches above the level of the lowest coil section 31'.

The invention disclosed in'the present application is particularly advantageous and eflicient because of the manner in which the solution circuit, condenser, and generator are shielded from the effects of the discharge pressure of the fan without affecting the operation of the absorber evaporator system and without permitting transient conditions in the absorber evaporator system to affect the flow within the solution circuit. Additionally, this arrangement provides a means whereby the level of the liquid on the gas lift pump can lie-maintained substantially constant which will permit the pump to operate under uniform conditions and at its -maximum efiiciency. This is highly important for the reason that any fluctuation in the rate of discharge rator are connected by a U-shaped conduit 60 from the gas lift pump immediately produces undesirable action in the absorber. Such action may take the form of improper stripping of the inert gas in the case of too small a discharge from the circulating pump, or it may cause weak solution to discharge into the analyzer in the event of too rapid discharge from the gas lift pump. Obviously, either of these conditions will produce undesirable conditions throughout the circuit because the evaporator either will not be properly supplied with liquid refrigerant or it will be supplied with rich gas which will inhibit proper evaporation of the refrigerant.

Though the invention has been illustrated and described in connection with a particular type of evaporator, absorber, heat exchanger, etc., it is not limited thereto as other types of these elements may be utilized which will create the same problems with respect to pressure differentials and which may be solved by this invention. For example, high pressure differentials are produced in the type of system in which the inert gas is introduced into a body of liquid to circulate the same and/or to be brought into contact with the liquid to facilitate evaporation or absorption.

While the invention has been illustrated and described herein in considerable detail, it is not to be limited to the constructional details illustrated and described. Various changes in construction, arrangement and proportion of the parts may be made without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. Refrigerating apparatus comprising a solution circuit including a boiler-analyzer and an absorber, a pressure equalizing medium circuit including an evaporator and said absorber, power operated means for producing flow of the pressure equalizing medium in said circuit, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase including a liquid pressure balancing means, and means venting the boiler-analyzer side of said pressure balancing means to a low pressure portion of said solution circuit.

2. Refrigerating apparatus comprising a solution circuit including a boiler and anabsorber, a pressure equalizing medium circuit including an evaporator and said absorber, means for producing flow of the pressure equalizing medium in said circuit, a gas lift pump in said solution circuit for circulating the solution, means for introducing pressure equalizing medium flowing in said pressure equalizing medium circuit into said gas lift pump to operate the same, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase including a liquid pressure balancing means, and means venting the boiler side of said pressure balancing means to a low pressure portion of said pressure equalizing medium circuit.

3. In an absorption refrigerating'apparatus of the type including a boiler, an absorber and a means for placing a pressure equalizing medium under pressure that improvement which includes the steps of subjecting the strong solution outlet on the absorber and the strong solution inlet on the boiler to substantially the lowest pressure prevailing in the system and subjecting the weak solution line between the boiler and the absorber to substantially the lowest pressure prevailing in the system.

4. Refrigerating apparatus comprising a solution circuit including a boiler-analyzer and an absorber, a pressure equalizing medium circuit including an evaporator and said absorber. means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase, means venting said supply means to a portion of said circuit containing pressure equalizing medium, a reservoir in the weak solution portion of said solution circuit, and means venting said reservoir to a low pressure area of the apparatus.

5. Refrigerating apparatus comprising a solution circuit including a boiler and an absorber, a pressure equalizing medium circuit including an evaporator and said absorber, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase including a liquid pressure balancing means, means venting the boiler side of said pressure balancing means to a low pressure portion of the apparatus, a reser- 1 voir in the weak solution portion of said solution circuit, and means venting said reservoir to a low pressure area of said pressure equalizing medium circuit.

6. That improvement in the art of refrigeration which includes the steps of propelling a pressure equalizing medium under pressure through an evaporating zone, generating refrigerant vapor in a generating zone, liquifying such vapor in a liquifying zone, supplying the refrigerant so liquified to the evaporating zone,

and shielding the generating and liquifying zones,

from the effects of the pressure prevailing in the evaporating zone caused by the propelled equalizing medium by forming a pressure balancing liquid column between the evaporating and generating zones, the propelling of said pressure equalizing medium being performed independently of each of said foregoing steps.

7. Refrigerating apparatus comprising a boiler, a condenser, an evaporator, and an absorber connected in circuit to form an absorption refrigerating system, power driven means operable independently of factors within said apparatus for circulating a pressure equalizing medium through a circuit including the absorber and the evaporator, the arrangement being such that the evaporator is connected to the high pressure side of said circulating means and the absorber is connected to the low pressure side of said circulating means, means for conveying weak solution from the boiler to the absorber, means for conveying strong solution from the absorber to the boiler, andmeans for maintaining the condenser, boiler, and absorber under the pressure prevailing on the low pressure side of saidcirculating means.

8. Refrigerating apparatus comprising a boiler, a condenser, an evaporator, and an absorber connected in circuit to form an absorption refrigerating system, power driven means for circulating a pressure equalizing medium through a circuit including the absorber and the evaporator, the arrangement being such that the evaporator is connected to the high pressure side of said circulating means and the absorber is connected to the low side of said circulating means, means for conveying weak solution from the boiler to the absorber including a reservoir and a gas lift pump connected between the reservoir and the absorber, means for introducing pressure equalizing medium from the high pressure side of said circulating means into said gas lift pump.

9. Refrigerating apparatus comprising an evaporator, an absorber, a boiler-analyzer, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase, means for propelling a pressure equalizing medium under pressure through a circuit including said evaporator and absorber, said evaporator and absorber being connected respectively to the pressur and suction sides of said pressure equalizing medium circulating means, means for conveying strong solution from said absorber to said analyzer, means for conveying weak solution from said boiler to said absorber, and means ,for equalizing the pressures prevailing in said analyzer and in the portion of said absorber from which the strong solution is removed.

.10. Refrigerating apparatus comprising an evaporator, an absorber, a boiler-analyzer, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase, means operable independently of factors within said apparatus for propelling a pressureequalizincluding said evaporator and absorber, said evaporator and absorber being connected respectively to the high and low pressure sides of said pressure equalizing medium circulating means, means for conveying strong solution from said absorber to said analyzer, means for conveying weak solution from said boiler to said absorber,

and means for equalizing the pressures prevailing in said boiler-analyzer and in the portion of said absorber to which the weak solution is conveyed.

11. Refrigerating apparatus comprising an evaporator, an absorber, a boiler-analyzer, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase, means for propelling a pressure equalizing medium under pressure through a circuit including said evaporator and absorber, said evaporator andabsorber being connected respectively to the pressure and suction sides of said pressure equalizing medium circulating means, means for conveying strong solution from said absorber to said analyzer, means for conveying weak solution from said boiler to said absorber, and means for equalizing the pressures prevailing in said analyzer and in the portion of said absorber from which the strong solution is removed, said strong solution conveying means being mounted in heat exchange relationship with said boiler and analyzer.

112. That method of shielding portions of an absorption refrigerating'system of the type utilizing a power driven pressure equalizing medium circulator from the pressure developed by such circulator which includes the steps of forming a pressure balancing liquid column between portions of the system which are to be shielded evaporator is connected to the high pressure side ofsaid circulating means and the absorberis connected to the low side of said circulating means,

means for conveying weak solution from the boiler to the absorber, means for conveying strong solution from the absorber to the boiler. means for maintaining uniform pressure conditions in said condenser, boiler and absorber comprising a connection from said condenser to said pressure equalizing medium circuit including a pressure balancing liquid column forming element, and a vent connecting the condenser side of said column forming element and a low pressure area of said pressure equalizing medium circuit. c

14. Refrigerating apparatus comprising a boiler, a condenser, an evaporator, and an absorber connected in circuit to form an absorption refrigerating system, power driven means for circulating a pressure equalizing medium through a circuit including the absorber and the evaporator, the arrangement being such that the evaporator is connected to the high pressure side oi' said circulating means and the absorber ing medium under pressure through a circuit is connected to the low side of said circulating means, means for conveying weak solution from the boiler to the absorber, means for conveying strong solution from the absorber to the boiler, means for shielding said condenser, boiler and absorber from the high pressure side of said evaporator comprising means connecting the pressure equalizing medium inlet and outlet portions of said evaporator and adapted to maintain a pressure balancing liquid column, and means for conveying refrigerant liquid from the condenser to the side of said connecting means connected to the pressure equalizing medium outlet of said evaporator.

15. An absorption refrigeration apparatus comprising a boiler, an absorber, an evaporator and a condenser connected in circuit, said cir cuit including an absorption solution circuit connecting the boiler and absorber and an inert gas circuit connecting the absorber and evaporator, power driven means for circulating the inert gas in its circuit including means for con ducting inert gas into the absorption solution circuit to promote the circulation of the solution through the boiler and the absorber, means connected between the inert gas circuit and said boiler operable to prevent the pressure developed on the discharge side of said inert gas circulating means from being. transmitted to said condenser, and means connected between said last named means and said boiler operable to return inert gas which may be present in the condenser back to said inert gas circuit. a

16. In a three fluid absorption refrigeration apparatus, the combination of a boiler assembly, an air-cooled absorber positioned at a higher elevation than said assembly, a solution reservoir below the upper portion of said absorber, conduits connecting said boiler,'reservoir and absorber in a closed circuit, said reservoir being in'a conduit conveying lean solution from the boiler to the absorber, a power driven fan operable to supply a gas under pressure to the lean solution conduit at a point between the reservoir and the absorber to elevate lean solution into the upper portion of the absorber, and means including a vent conduit providing communication between said reservoir and said absorber.

17. A three fluid absorption refrigeration sys-' venting the condenser to the inert gas circuiton the low pressure side of said gas circulating means.

18. In a three fluid absorption refrigeration system, a condenser for liquefying refrigerantvapor, an evaporator, an absorber, means connecting said evaporator and absorber in circuit, an inert gas in said circuit and means for positively circulating the gas therethrough, said system being characterized by a liquid seal conduit connecting said-condenser to the inert gas inlet side of said evaporator whereby the pressure on the discharge side of said gas circulating means is balanced by a liquid column in said liquid seal, and a vent leading from the condenser side of said seal to the gas outlet from said I evaporator.

19. In combination with a three fluid absorption refrigeration system, an evaporator vessel, an absorber, means forming an inert gas circuit between said evaporator and absorber and including a power driven means for circulating the gas having its intake side connected to the absorber and its discharge side connected to the evaporator, a boiler, an absorption solution reservoir, means for conducting lean solution from the boiler to the absorber through said reservoir, means for by-passing inert gas from the discharge said of said gas circulating means into the lean solution conduit at a point intermediate said reservoir and the absorber and at a point below the liquid level in said reservoir whereby 'the absorption solution is elevated into the absorber, and means for equalizing the pressure in said reservoir and the supply side of said gas circulating means whereby the pressure difierential between the supply and discharge sides of the gas circulator is available to elevate said lean solution.

20. In an absorption refrigeration system havthe same into .said gas lift pump to elevate solution therein, and means providing free communication between the discharge side of said pump, said reservoir and a low pressure area in said inert gas circuit whereby pressure fluctuations in said system will be reflected to both the inlet and discharge sides of said gas lift pump.

23. In an absorption refrigeration system of the type employing a boiler, a condenser, an evaporator, and an absorber interconnected in circuit and including an inert gas circuit between said absorber and said evaporator and an absorption solution circuit between said boiler and said absorber, said last mentioned circuit including a first conduit for conveying lean solution from the boiler to the absorber and a secand conduit for conveying enriched solution from the absorber back to the boiler, one of said conduits including an absorption solution reservoir and an inert gas operated gas lift pump, a power operated gas impeller for circulating inert gas in its circuit, means for by-passing gas under pressure from the discharge side of said ing a boiler, a condenser, an evaporator and an absorber connected in circuit and including conduits providing an absorption solution circuit between said absorber and said boiler, a solution reservoir in said solution circuit, a gas lift pump forming part of said solution circuit and having the inlet thereof connected to said reservoir, a power operated gas impeller for supplying gas under pressure to said pump to elevate solution therethrough, and means interconnecting the discharge side of said gas lift pump and the gas space above a liquid level in said reservoir whereby pressure fluctuations in said system will have a minimum eifect upon the operation of said gas lift pump and the rate of solution circulation in said solution circuit.

21. In an absorption, refrigeration system of the type having a boiler, a condenser. an evaporator, and an absorber connected in circuit, said circuit including an absorption solution circuit between said boiler and said absorber, a solution reservoir and a gas lift pump connected in series in one side of said solution circuit, a power operated impeller for circulating an inert gas between said absorber and said evaporator, means for conveying inert gas under pressure into said gas lift pump to elevate absorption solution and thereby cause the same to circulate through the solution circuit, and means interconnecting the space above the liquid in the solution reservoir and the discharge side of said gas lift pump to a low pressure area whereby pressure fluctuations in said system will be equalized at the inlet and discharge sides of said gas lift pump.

22. In an absorption refrigeration system of the type having a boiler, a condenser, an evaporator, an absorber, interconnected in circuit, and including an absorption solution circuit between said boiler and said absorber and an inert gas circuit'between said absorber and said evaparator, a power operated impeller in said inert gas circuit for circulating the gas insaid circuit, an absorption solution reservoir and a gas lift pump. connected in series in said solution circuit, means for by-passing inert gasunder pressure from said inert gas circuit and delivering impeller into said gas lift pump to elevate solution therein, and means including a liquid-free passageway interconnecting said reservoir and the discharge end of said gas lift'pump for maintaining substantially constant pressure conditions at the inlet and discharge ends of said gas lift pump.

24. In combination, an absorption refrigeration apparatus comprising a boiler, a condenser, an evaporator and an absorber interconnected in circuit and including an inert gas circuit between said absorber and said evaporator and conduits providing an absorption solution circuit between said boiler and said absorber, one of said solution conduits including a solution reservoir and a gas lift pump having its inlet connected to receive solution from said reservoir and its discharge and located at a level above said reservoir, said reservoir having a capacity such that solution level differences of comparatively large magnitude in the boiler will produce solution level differences of low magnitude in said reservoir, a gas lift pump connected to receive liquid from said reservoir and having its discharge positioned above said reservoir, a power operated impeller for introducing a medium in gaseous phase into said pump to cause elevation of solution therein, and means including a normally liquid-free passageway interconnecting the spaces surrounding the inlet and discharge sides of said pump respectively whereby a pressure change in either space is immediately transmitted directly to the other space.

25. In combination, an absorptionrefrigeration system comprising a refrigerant vapor generator, a refrigerant vapor liquefier, an evaporator, and an absorber interconnected in circuit, said circuit including an inert gas circuit between said absorber and said evaporator and conduits providing an absorption solution circuit between said vapor generator and said absorber, power operated means for circulating inert gas in said inert gas circuit, means including a column of liquid refrigerant between said evaporator and said liquefler for preventing excess pressures in said inert gas circuit from being'transmitted to said liqueiier and said vapor generator, a vent extending from a point on the low pressure side of said. liquid column to a low pressure area in said inert circuit, said absorption solution circuit including a gas lift pump for circulating the solution through its circuit, and means providing free communication between the inlet and discharge pressure area in said inert gas circuit whereby pressure changes in said system havea minimum eilect upon the rate of absorption solution circulation and upon the operation of said gas lift D D- a 26. In combination, an absorption refrigeration apparatus including a refrigerant vapor generation conduit also including a gas lift pump having 1 its inlet end in communication with the solution within said reservoir and its outlet at a point above said reservoir, means for supplying a medium in gaseous phase to said gas lift pump to elevate solution therein whereby the solution fiows through the remainder of the solution oircuit by gravity, and means for maintaining the inlet and outlet of said gas lift pump under subsides of said gas lift pump and connected to a low stantially the same pressure conditions whereby the rate of solution circulationis unafijected by pressure fluctuation within the apparatus.

27. In combination, an absorption refrigeration apparatus including a refrigerant vapor generator, an air-cooled tubular absorber having a portion located above a portion of said generator, a first conduit for conveying weak solution from a lower portion of said generator to a portion of said absorber located at a higher elevation, a second conduit for returning enriched solution from said absorber to said generator, said first conduit including a solution reservoir and a twin gas lift pump connected in series therewith, the

inlet for said twin gas lift pump being connected to said reservoir and the outlet of said pump being located at an elevation above said reservoir, means for supplying gas under pressure to said twin gas lift pump to operate the same, and means including a normally liquid free conduit providing free communication between the outlets and the inlet of said pump and a low pressure area to insure maximum effectiveness of said twin gas lift pump and to reduce the effect of pressure changes at the oppositeends of said pump to a minimum.

CURTIS C. COONS.

RUDOLPH ,S. NELSON. 

